What's the purpose of electric fan shutoff delay?

[SunSoaked]

My Dakota Digital fan controller allows me to keep the fans running for 30 second, 1,2 minutes after engine is shut off. I have it set at 30 sec but I'm about to switch my Viper alarm to passive mode. In other words, it arms itself 30 seconds after the ign is off and the door closes.
In reality, I doubt the airflow really matters if the engine is off and there's no coolant circulating.
However, I'm guessing if the alarm arms itself and sees a current draw it will set it off or cancel the arming.

[RADustin]

I don't think the current draw would mess up the alarm. ?


You still have coolant flow after the engine is shut off. as the coolant in the rad cools faster than the coolant in the block, it will naturally keep moving a small amount. keep in mind the block is many times hotter than the coolant, so when you shut off and let it sit, that coolant in the block heat soaks and conducts and flows a small amount to the coolant in the rad. So running the fan longer than your heat source(engine) allows for a decent control of this heat spike.